New York City telephone exchanges

The history of the telephone exchange names in New York City can be divided into
three periods:

The pre-dial period, covering directories dated
prior to November 17, 1920 (the last being dated May 1920), when all telephone calls
were completed by manual action by operators, and there were no constraints on
exchange names other than that there was no likelihood of confusion when a customer
gave the name to the operator,

The late dial period, beginning with the
directory dated Winter 1930, in which, instead of the first three
letters of an exchange name, one dialed only the first two letters and
an "office number" (This was the terminology used in the Winter
1930 directory, though it was not common terminology in this period), again followed
by (usually) four digits designating the individual line. Although, in 1930,
New York City was alone in using this pattern, it eventually became the common
format for dialed telephone numbers in the United states until the advent of
All-Number-Calling in the 1960s.

It should be noted that on this site we do not refer to the pre-dial period as the
"manual" period, because (as noted above) manual exchanges continued to exist for
many years into the dial period. What distinguishes the pre-dial period from the
early (and late) dial period was not the presence of manual exchanges,
but the absence of dial exchanges.

The varied changes in directory formats during these three periods are
separately discussed in the pages covering each individual period (which
can be reached by clicking the appropriate links either in the preceding
paragraph or in the table listing the chronological periods below).

This site includes information about
other telephone numbers northward and eastward of New York City, because
some of those numbers became dialable from the city after about 1950, while
others were, in turn, connected with those suburban numbers by being assigned
the same area codes when area codes were instituted, and as a result they
affected the availability of exchange names. (See this page for more information.)